Experimental Investigation of Material Constant for Perforated Plate

Abstract

RCC-MR (2007) has been used as a design/manufacturing code for intermediate heat exchanger (IHX) in Prototype Fast Breeder Reactor (PFBR). The code uses equivalent solid plate (ESP) methodology for modeling a tube sheet to carry out stress analysis. Structural integrity assessment of tube sheets with ESP concept is the same as that of solid plate except that it uses an effective elastic constant (E* and ν*) in place of the actual material constants, E and ν. In the latest version of design code RCC-MRx (2012), values of effective elastic constants are provided for circular pitch pattern. Effective Young’s modulus E* and Poisson’s ratio ν* values are provided for the ligament efficiency (η) range between 0.1 to 0.6 and 0.3 to 0.6, respectively. In case of PFBR-IHX and IHX of future reactors, ligament efficiency of tube sheet is ~0.255 for which effective Poisson’s ratio ν* value is not available in design codes as well as in the open literature and also it cannot be extrapolated. Hence, an experiment was conducted to obtain the load–deflection curve, extract the values of strain and subsequently estimate the effective elastic constant (ν*). Toward this, scaled down IHX tube sheet models (3 Nos. perforated plates) of desired ligament efficiency were employed. In this paper, the experimental setup, load–deflection curve for IHX tube sheet scaled-down models, strain in tube sheet, estimation of ν*, comparison of experimental results with Finite Element(FE) analysis results are discussed. It is observed that (i) the measured deflection values near the inner edge are higher than the FE analysis values in actual model and, (ii) in ESP model, for material constants of E* and ν* (calculated from experiment), the achieved deflection values at various radial locations closely match with the experimental results and hence, can be used for modeling of equivalent solid plates.